Reply to: Preferred Method for the Diagnostic Evaluation of Ground-Glass Opacities

I thank the Author/s for their observations. I think that an aggressive approach should be the main approach in solitary lung nodule management when preoperative diagnosis with bronchoscopy, CT-guided needle biopsy or video-assisted thoracoscopy is impossible. A preclinical diagnosis of lung cancer is fundamental for radical surgical treatment. Gajra et al. [1], studying 246 non-small cell lung cancer patients with stage IA lesions (diameter of the lesion ≤ 1.5 cm [86 patients] or between 1.6 and 3 cm [160 patients]), reported a 5-year survival rate of 85.5 % for the first group and of 78.6 % for the second group. The disease-free survival rate was 81.5 % and 70.9 %, respectively. Li et al. [2] reported that the 5-year survival rate for patients with tumour sizes < 2 cm was 75.49 %, while the survival rate of those with lesions > 7 cm was 46.15 %. Disease-free survival rates were 67.65 % and 30.77 %, respectively. Considering the variable nature of ground-glass opacity (GGO), I think that waiting is contraindicated. Follow-up thin-section CT for up to 16 months that highlights the increase of the solid component of the GGO malignant lesion [3] leads to delayed diagnosis of lung cancer. In our study [4], GGO was found in 9 of 124 patients with non-calcified single-lung nodules. 18-Fluorine fluorodeoxyglucose positron emission tomography with computerised tomography (¹⁸F‐FDG PET/CT) characterised those lesions better in which subsequent histopathological examination identified idiopathic nonspecific interstitial pneumonia with cellular inflammation components according to Katzenstein and Fiorelli [5]. The results of Chun et al. [6], who analysed 14 pure ground-glass nodules and 54 part-solid nodules in 45 patients, discourage the use of ¹⁸F‐FDG PET/CT but confirm the necessity of a mini-invasive or open biopsy for the evaluation of GGO. Nakayama et al. [7], in 201 T1N0M0 adenocarcinoma patients, showed that a higher maximum standardised uptake value on PET/CT was linked to the degree of malignancy.

In conclusion, I am of the opinion that management of a indeterminate single lung nodule can include a short follow-up (≤ 3 months) with ¹⁸F‐FDG PET/CT or thin-section CT of the thorax. In cases where unchanging images provide information to the diagnostician, open surgery is necessary, as this permits a definitive histological characterisation of the lesion.

References

• 1 Gajra A, Newman N, Gamble G P, Abraham N Z, Kohman L J, Graziano S L. Impact of tumor size on survival in stage IA of non-small cell lung cancer: a case of subdividing stage IA disease.  Lung Cancer. 2003;  42 51-57
• 2 Li Z, Yu I, Lu J et al. Analysis of the T descriptors and other prognosis factors in pathologic stage I non-small cell lung cancer in China.  J Thorac Oncol. 2009;  4 702-709
• 3 Park C M, Goo J M, Lee H J, Lee C H, Chun E J, Im I G. Nodular ground-glass opacity at thin-section CT: histologic correlation and evaluation of change at follow-up.  Radiographics. 2007;  27 391-408
• 4 Divisi D, Di Tommaso S, Di Leonardo G, Brianzoni E, De Vico A, Crisci R. 18-fluorine fluorodeoxyglucose positron emission tomography with computerized tomography versus computerized tomography alone for the management of solitary lung nodules with diameters inferior to 1.5 cm.  Thorac Cardiovasc Surg. 2010;  58 422-426
• 5 Katzenstein A L, Fiorelli R F. Nonspecific interstitial pneumonia fibrosis: histologic features and clinical significance.  Am J Surg Pathol. 1994;  18 136-147
• 6 Chun E J, Lee H J, Kang W J et al. Differentiation between malignancy and inflammation in pulmonary ground-glass nodules: the feasibility of integrated (18)F-FDG PET/CT.  Lung Cancer. 2009;  65 180-186
• 7 Nakayama H, Okumura S, Daisaki H et al. Value of integrated positron emission tomography revised using a phantom study to evaluate malignancy grade of lung adenocarcinoma: a multicenter study.  Cancer. 2010;  116 3170-3177